Modify AR15 A2 barrel extension for M4 feed ramp?

[js2013]

Wondering if anyone has modified an ar15 A2 barrel extension to work with an upper receiver with M4 feed ramps?

 

[Cemetery21]

Sorta. I've modified barrel/receivers even before M4 cuts came out and done some receivers when the barrels had cuts. Should not be too hard. Insert the barrel and sharpie the cut area, then use the right bit on a dremel. Check often for fit. This is one time it's better to go a little too far than to leave an edge for the round to catch.

 

[mac86951]

It's doable with a dremel and carbide bit.

Question, aside from modifying the barrel extension feed ramps, you'll run into other issues too. A2 uppers are available. Brownells and others. My advise is to replace the barrel assembly, or replace the extension and re-headspace.

 

[Fast14riot]

Just use a dremel or round file. Not a big deal. Just try not to gouge the receiver until you're ready to blend them in.

 

[Cemetery21]

And while you are in there with your dremel, soften the feed ramp and the inside corners of the two lugs that scratch brass on extraction.
A chain saw sharpening bit can be used for the M4 cuts if you don't a good fitting bit.

 

[js2013]

And while you are in there with your dremel, soften the feed ramp and the inside corners of the two lugs that scratch brass on extraction.
A chain saw sharpening bit can be used for the M4 cuts if you don't a good fitting bit.

Thanks. Good advice. Using the sharpie to mark the cut area is a really good idea too.

 

[js2013]

Did the modification today. Came out very nice, easier than I expected. Thanks for everyone's help.